Armed with a small spear and the light of a kerosene lantern, many fishermen of the Danajon Bank in the Philippines eke out a living by spearing fish at night. Most of the fish are smaller than the average human hand, clearly indicating how heavily overfished this once productive region is. Photo by Thomas Peschak

Armed with a small spear and the light of a kerosene lantern, many fishermen of the Danajon Bank in the Philippines eke out a living by spearing fish at night. Most of the fish are smaller than the average human hand, clearly indicating how heavily overfished this once productive region is. Photo by Thomas Peschak

A Galapagos shark swims the shallows of Bassas da India, an atoll in the channel between Mozambique and Madagascar. This small atoll is one of the most pristine parts of the Indian Ocean, a place where shark populations are still relatively healthy. Photo by Thomas Peschak

A Galapagos shark swims the shallows of Bassas da India, an atoll in the channel between Mozambique and Madagascar. This small atoll is one of the most pristine parts of the Indian Ocean, a place where shark populations are still relatively healthy. Photo by Thomas Peschak

A humpback whale bubble-net feeding in the Pacific Ocean off Canada's Great Bear Rainforest. When using this feeding technique, humpback whales coordinate their movements, blowing veils of bubbles to encircle and concentrate their fish prey before gulping them up. Photo by Thomas Peschak

A humpback whale bubble-net feeding in the Pacific Ocean off Canada's Great Bear Rainforest. When using this feeding technique, humpback whales coordinate their movements, blowing veils of bubbles to encircle and concentrate their fish prey before gulping them up. Photo by Thomas Peschak

Hanifaru Marine Protected Area in the Maldives is thought to be the location of one of the largest aggregations of manta rays anywhere in the world. As such, it promises tourists an opportunity to swim with dozens of mantas. Scores of visitors arrive each year hoping to witness the mantas' seasonal feeding frenzy. Photo by Thomas Peschak

Hanifaru Marine Protected Area in the Maldives is thought to be the location of one of the largest aggregations of manta rays anywhere in the world. As such, it promises tourists an opportunity to swim with dozens of mantas. Scores of visitors arrive each year hoping to witness the mantas' seasonal feeding frenzy. Photo by Thomas Peschak